Closed system hydraulic pump



April 22, 1952 c. J. COBERLY 2,593,729

CLOSED SYSTEM HYDRAULIC PUMP Filed July l, 1946 5 Sheets-Sheet l Apri 22, 1952 c. J. coBERLY CLOSED SYSTEM HYDRAULIC PUMP 5 Sheets-Sheet 2 Filed July l, 1946 April 22, 1952 c. J. COBERLY CLOSED SYSTEM HYDRAULIC PUMP 5 Sheets-Sheet .5

Filed July l, 1946 fA/z/f/vrof? knee/vof d CoM/2u 6r H/s ArToR/vfrs; h #4R/PAS, A7506; @WHEN/AMBAS,

Patented Apr. 22, v1952 UNITED 'res CLOSED SY STEM HYDRAULIC PUMP Clarence J. Coberly, Los Angeles, Calif., assignor, by mesne assignments, to Dresser Equipment Company, Cleveland, Ohio, a corporation of Ohio Application July 1, 1946, Serial No. 680,679

(Cl. S- 46) 8 Claims.

This invention relates to fluid operated well pumps, and more particularly, to a closed system of supplying operating fluid to such a pump.

In conventional fluid operated well pumps, operating uid is supplied thereto under relatively high pressure through a power tubing extending downwardly in the well. As is well known in the art, such operating fluid is alternatively directed by a suitable valve in the pump mechanism to opposite ends of a motor piston which is coupled by a suitable piston rod to the piston of a displace' ment pump. By such application of operating uid to the power piston it, and consequently. the pump piston, is reciprocated to pump well fluid from the well, such well fluid normally being conveyed upwardly to the ground surface by a production tubing. In such a pump it is conventional practice to discharge the spent operating fluid from the motor cylinder into the column of pumped well fluid so that they are intermixed and conveyed upwardly together through the production tubing. As the operating fluid supplied to the pump must be clean, to prevent abrasion of the moving parts, fresh clean operating uid must be continuously supplied to the system. The continuous provision of such fresh operating uid requires considerable equipment, normally in the form of settling tanks or filters, all of which is expensive.

' It is therefore a primary object of this invention to provide a separate closed system for such 'operating fluid, so that instead of mixing it with the well production as mentioned above, it is separately conveyed back to the surface of the ground'for storage and re-use to actuate the fluid operated pump. With such a closed system there is relatively little loss of operating uid therefrom, and, consequently, the equipment provided to supply fresh, clean operating uid to the system need have only a relativelysmall capacity and can be relatively cheap and economical. Further objects of the invention, of course, reside in certain required modifications of the pump, and in the well tubing employed to provide such a closed system.

In the conventional operation of a fluid-operated pump a high pressure oil pump, usually of the triplex type, is employed on the ground surface to convey the operating fluid under high pressure tothe well pump. The specic construction ofsuch a triplex pump is well known in the art and I`forms no part of the present invention. However, it is important to note that such triplex pumps are normally equipped with an auxiliary scavenger pump of small capacity which adds back into the system on the intake side of the triplex all leakage therefrom which is separately collected.

It is a further object of this invention to employ such scavenger pump to replenish to .such

a closed operating uid system as described such additional operating fluid as may be required due to leakage in the well pump or power tubing.I To accomplish this, I provide a reservoir of operating fluid which is connected to the scavenger pump by a valved line so that by opening the valve the scavenger pump can add fluid from the reservoir to the closed system as desired, and this is an additional object of the invention.

It is a further object of the invention to provide such a closed system in which the uid reservoir is operatively connected to the scavenger pump in response to a reduction of the total volume of fluid in the closed system, due to leakage therefrom or otherwise. I prefer to accomplish this by providing a collection tank connected to the intake of the triplex pump, into which tank the spent operating fluid from the well discharges, and to provide float means in such tank Which moves in response to a change in the total volume of operating fluid in the closed system to control the valve between the reservoir and the scavenger pump. By such a combination, at any time that the total volume of operating uid in the closed system falls below a predetermined minimum, such valve is opened to permit the scavenger pump to draw additional operating uid from the reservoir and to introduce it into the closed system until the total volume of operating fluid in the system has been increased by a predetermined amount, at which time the oat means closes the valve. These features of construction are additional objects of the invention.

Still another object of the invention is to provide a double-Walled well tubing in which the inner and outer walls are spaced but rigidly joined together so that they may be easily handled as a joint or section assembly. n

Another object of the invention is te provide a coupling for such double-walled tubing joints, such as to form uuid-tight couplings between the inner and outer tubings, respectively, of adjacent joints of the tubing.

A further object of my invention is to supply a coupling for stands of such double-walled tubing such as to form such fluid-tight couplings and further so as to retain in each stand of the tubing, as it is broken from the stand below, any operating fluid contained therein. This prevents loss of such operating uid and avoids what is known in the industry as a wet pulling job as the tubing is withdrawn from the well. I prefer to accomplish this by providing suitable valves in each coupling such as to close both the inner and outer tubings as the coupling is broken, which is ralso an object of the invention.

Other objects and advantages will appear Vfrom the following specification and the drawtubing joints.

Fig. is a cross-sectional view taken on the line 5-5 of Fig. 4; v

Fig. 6 is an enlarged vertical sectional View of the tubing coupling of my invention;

Fig; 'l is a cross-sectional view taken on the Fig. 8 is an enlarged longitudinal sectional view taken through the special elbow-type coupling of the invention;

' "Fig 9 is an enlarged. longitudinal sectional view taken through a special separation fitting of the invention;

Fig. 10 is a cross-sectional View taken on the line Ill-Ill of Fig. 9;

Fig. 11 is an enlarged vertical sectional view taken through the upper end of my modified form-of uid operated well pump, showing the double-walled tubing connected thereto;

y Fig. 12 is a cross-sectional View taken on the line l2-l2 of Fig. 11;.

Fig. 13 is a cross-sectional view taken on the line I3-I3 of Fig.. 11; and

Fig. 14 is a cross-sectional view taken on the line lll-I4 of Fig. 1l.

Referring to Figs. 1 and 2, the drawings show a conventional well casing I5 set in a well, and

,havinga .production tubing I6 extending downwardly thereinto, the lower end of the production tubing vbeing provided with a pump seat il on which is seated a fluid operated pump I3. To

the upper end of the pump I8 is affixed a special inlettting I9 by which the pump is connected to power tubing 20, which extends upwardly through the production tubing. l

The power tubing 23 is formed cfa Yplurality of axially aligned tubing sections 22, 22a, and

22h, commonly referred to in the oil industry as For convenience of description, only threeof such tubing sections are shown, the tubing sections 22 and 22a being connected together by a tubing coupling 23,and the tubing sections 22aand 22o beingconnected together by a valved coupling 24. It will be understood by those familiar with the oil industry, however, that the power tubing in actual practice is normally made up of a large number of such tubing sections which are divided into stands of tubing, each stand comprising three or four tubing sections, and a valved coupling like the valved coupling 24 is provided at the lower end of. each stand. The remainingA tubing sections I in each of the stands are connected together by tubing couplings like the tubing coupling 23. The tubing sections 22, 22a, and 22hare generally similar in construction, and parts of the sections 22a and 22h which are similar to parts of the section 22 will be referred to by similar numerals as refer to the parts of the tubing section 22, but with the suflixes a and b added therett respectively.

The upper end of the production tubing I6 is coupled in a conventional manner to a standard.

vfitting 30 by a discharge line 35,

casing head 4which is provided with a discharge nipple 23 disposed so as to convey pumped well iiuid from the production tubing to a point of disposal or use (not shown) The upper end of the casing head 25 may be provided with conventional slips 2l, if.V desired, to additionally support the power tubing.v Connected to the upper end of the vertical portion of the power tubing 20 is a special elbow fitting 29, which directs the power tubing horizontally therefrom. to a separation fitting 30,

shown in Fig. 3. To the separation fitting is connected a spent power fluid line 3| which is adapted to convey spent power fluid from the fitting 33 to a collection tank 32 which is connected at its bottom by means of a flow line 33 to a'high pressure pumpl 34, preferably of the triplex type, which is adapted to Aconvey power fluid from the collection tank to the separation As will be understood, the pump 34'is disposed on the surface of the ground, and may be of any type desired which is adapted to supply power fluid to the line 35 under pressure suilicient to operate the fluid operated pump i8, as is generally well known in the art. As will also be noted in the embodiment illustrated the collection tank 32 is disposed substantially above the pump 34 so that power uid can ow by gravity under some inlet pressure from 'the collection tank to the pump. Obviously, means other than gravity may be provided for this purpose if desired. Also provided above the surface of the ground is an auxiliary tank 31 which constitutes a source of additional power iiuid, being supplied therewith as may be required through a valved inlet pipe38. The high pressure pump 34, as is Well known in the art, is.pro vided with an auxiliary pumping means (not shown) which is adapted tc return to the intake of the high pressure pump Vcommunicating with the flow line 33 any leakage that may occur in the pump. The auxiliary tank 31 is connected to the intake of such auxiliary pump by a iiuid line 39, so that when the fluid line is open the auxiliary pump may draw additional operating fluid from the auxiliary tank 31 and convey it to the intake of the high pressure pump 34, so as to replenish operating fluid lost from the power tubing 2 and fluid operated pump I8 during normal operation thereof. A float-actuated valve 40 is provided in the fluid line 39 and is operated by aconventional float mechanism 4l disposed in the collection tank 32,'the valve 40 and the float mechanism being mechanically connected by a suitable rod 42. As will be understood, when the total volumeofoperating fluid in the power tubing 20: decreases, due to leakage or other causes, the level thereof in the collection tank 32 will drop, and when the volume is reduced to a predetermined value the iioat mechanism 4| acting through the rod 42 will operate the float-actuated valve 40 to admit additional operating fluid from the auxiliary tank 37 to the auxiliary pump of the high pressure pump 34 through the fluid line 33, to replenish such fluid lost from the power tubing. When the fluid level in the collection tank 32 rises to a predetermined extent, the float mechanismr 4| will operate 'through the rod 42 to close the valve 4B. This mechanism, thus, automatically replenishes operating fluid lost from the power tubing 20 as may be required during operating of the fluid operated pump I8.

Referring to Fig. 11, the fluid operated pump I8 is provided with the inlet fitting I3 at its upper end, having a central bore 44 adapted to receive operating fluid from the power tubingv 20 and to convey it to the fluid operated pump to attuate the same. The inlet fitting I9 is also provided with a plurality of circumferentially spaced longitudinalV 'passages 45 which communicate with the upper end of the iitting and with an annular groove46 formed in the bore of the fitting. AS will be understood by those skilled in the art, the annular groove 46 is adapted to cooperate through suitable yvalve'mechanism, (not shown) to convey spent operating fluid from the motor cylinder of the fluid operated pump I8 to the longitudinal passages 45 so that the same may be discharged upwardly therethrough and into the power tubing 26.

As shown in Fig. 11, the lowermost tubing section 22 includes an outer tubing member 48 and an inner tubing member 49 concentrically disposed within the outer tubing member and spaced therefrom so as to provide an annular longitudinal space 50. The cuter and inner tubing members 48 and 49 respectively, are rigidly retained iny spaced relation, as shown, by two or more spacer bars 5I disposed therebetween and welded or otherwise rigidly secured to the tubing members. Also, asshown in Fig. 1l, the lower ends of the tubing members 48 and 49 are pro vided with conical seating faces 52 and 53, respectively, which are adapted to seat on and respectively form duid-tight engagement with conical seats 54 and 55, provided on the upper end of an insert member 56. The insert member 56 is provided with a central bore 51 which is axially aligned with the inner tubing member 49 and with the central bore 44 of the inlet iitting I9 so as to provide fluid communication therebetween. `The insert member 56 also has a plurality of circumferentially spaced longitudinal passages 58 which provide fluid communication between the annular longitudinal space 58 'of the power tubing 28 and the longitudinal passages 45 of the inlet fitting I9. The upper end of the inlet iitting I9 is provided with external threads adapted to receive internal threads of a coupling member 60, the upper end of which is internally threaded at 6I onto external threads 62 formed on the outer tubing member 48. It is to be noted that the outer tubing member 48 is provided with a straight tubular portion 63 below the threads 62, which portion is adapted to engage an annular resilient 0.-ring 64 carried in an annular groove 65 inthe coupling member 69, so as to form a duid-tight seal between the coupling member and v seats 61 and 6B, respectively, formed on an insert member 69. The insert member '69 is pro- A vided at its upper end with similar conical seats, which similarly engage conical seating faces 52a and 53a .formed on the lower end of the next sucseeding tubing section 22a. The tubing sections 22 and 22a, with the insert member 69 therebetweenin the position illustrated in Fig. 6, are adapted to be rigidly clamped together by the tubing coupling 23 which is threaded to the outer tubing member 48 of the tubing section 22 and to the outer tubing member 48a of the tubing section 22a. The coupling 23 is provided with a pair of spaced annular grooves 16 and 1|, containing resilient O-rings. 12 and 13, respective- 6., 1y. which engage in huid-tight relation to the lower and upper ends of the tubing sections 22a and 22, respectively. The insert member 69 is provided with a central bore 14 which is axially aligned with the bores of the inner tubing members 49 and 49a so as to provide fluid communication therebetween, and is provided with circumferentially spaced longitudinal passages 15 which provide fluid communication between the annular space 50 and the annular space 50a. As will also be noted, the upper end of the tubing section 22 is also provided with spacer barsl Sla, which are similar to the spacer bars 5I shown in Figs. 11 and 14, and the tubing section 22a is similarly provided with spaccil bars at each of the ends thereof.

As best shown in Fig. 4, the tubing sections 22a and 22h are rigidly connected together by the valved coupling 24. The tubing sections 22, 22a, and 22h have substantially identical constructions, with the exception that the upper end of the tubing section 22a is provided with a transverse valve-actuating bar 11 welded or otherwise secured inthe inner tubing member 49a thereof for a purpose to be described hereinafter. The valved coupling A24 includes an outer tubular coupling member 18 which is generally similar to the tubular coupling 23 but is somewhat longer, similarly being provided with vannular 0-rings 19 and 88 adapted to form fluidtight seals with the lower and upper ends of the tubing sections 22h and 22a, respectively. Also, the central part of' the coupling member 18 is provided with an annular channel 8| and an inwardly projecting annular. shoulder 82 providing an outer valve seat 83. As will be noted, the shoulder 82 projects into the bore 84 of the coupling member 18.

Housed within the outer tubular coupling member 18 is a valve assembly 86 provided with upper and lower heads 81 and 88, respectively, the upper head havinga plurality of circumferentially spaced longitudinal passages 89 adapted to communicate vwith the annular space 59h of the tubing section 22h, and the lower head 88 being similarly provided with a plurality of longitudinal passages 99 adapted to communicate with the annular space 59a of the tubing section 22a. As illustrated, the valve assembly 86 is generally tubular in form, providing a central longitudinal passage 9| therethrough and having an external annular projection 92 providing an outer conical valve face 93 adapted to seat on the outer valve seat 83, and having an inner annular projection 94 providing an inner annular valve seat 95. Adapted to seat on the inner annulanvalve seat 95 isan inner valve member 91, of the poppet type, having a valve stem 98 supported for vertical movement relative to the inner valve seat 95 by crossbars 99 and |06 secured in or formed integrally with the valve assembly 86. The valve assembly 86 is also provided at its upper and lower ends with seating faces IOI, and |82, respectively, which are adapted to be engaged by the `Alower end of the tubing sections 22h and the .upper end of the tubing section 22a, respectively, in fluid-tight engagement. The operation ofthe valve coupling 24 will be described hereinafter.

Referring to Fig. 8 of the drawings, the elbow fitting 29 includes a vertical tubular portion |84 which is adapted to threadedly receive the upper .end of the outer tubing member 48h of the tubing section 22h, and is provided with a horizontal tubular portion adapted to threadedly screws |31.

7 receive Aone 'end 'of `a`t'ubin'g' section 22c.` vThe elbow fitting is provided with central bores |88 and |91 which intersect to form a central passage therethrough, and is provided with drilledpassages |98 and |09 which communicates through drill portg` H8 o an insert member III with the annular longitudinal space 55h of the tubing section 22D. The passages |88 and |89 also communicate through ports I I2 of an insert member `H3 with an annular longitudinal space 53e of the horizontal tubing section 22e. Similarly, the central bore |85 communicates through a bore |I4 Vin the insertmember ||I 'with the bore of the inner' tubing member 49h, and the central bore I01 communicates through a bore |I5 of the insert member I I 3 with the bore of the inner tubular member 49e of the horizontal tubingfsection 22e. The elbow iitting 29 is provided with conical seats Hb` and II1 against which the insert members illand IIS, respectively, seat to form fluidtight engagement with the elbow fitting. Similarly, the insert members I|I and lI I3lseat against conical seats IIB and |I9 of the inner tubing members 49h and 49e, respectively, to form fluid-tight engagement therewith. In this form of construction, however, the elbow fitting 29 is cut away at |28 and |2I so that no huid-tight fit is made between the insert mem- -bersI'Il and II3 and the outer tubing members 48h and- 48e, respectively, the seal between such outer tubing members and the elbow fitting being provided by O-rings |22 and |23. As will be understood, the elbow tting 29 secures the tubing sections 22h and 22e together so as to provide a pair of fluid paths therebetween.

i Referring to Figs. 9 and 10 cf the drawings, the separation fitting 3D provides a connection between the horizontal tubing Isection 22o and containing an O-ring |29 adapted togiorm a duid-tight seal between the periphery of the tubing section 22e and the iitting 38. Between the bore |25 and the counterbore |26 is a conical seat |38 against'which an insert member YI3I seats in fluid-tightv relation. The insert member IBI-fis provided with anvannular cut-away portion '|32 and with circumferentially spaced -longitudinalports |33 which communicate with the annularlongitudinal space 158e of the tubing ',section'22c.- `The cut-away portion |32^alsccom- 'municate's through a radial port |35 witha tting |33 welded or otherwise secured to the end of the spent power fluid line 3| and detachably connected to the -separation tting 38, as by The central bore |25-likewise communicates through a radial port |38 with a fitting u|39, similar to the tting |36, and welded or otherwise secured to the end of the `discharge Ymay be accomplished by manuallyv opening the valve in the inlet pipe 38 and the float actuated .valve 48 so that operation of the high` pressure pump 34 can introduce operating fluid through the discharge line 35 and the separation fitting 38 to the power tubing. As will be understood --from Fig. 9, such operatingY fluid, `under substantial pressure, passes into -the separation fitting 30' from the' discharge' line 35,- through the'insert' member |3I, and into the inner tubing member 49e of the tubing section 22e, from whence it continues through the elbow fitting 29 and downwardly through the inner tubing members of the power tubing 29 to the inlet iitting I9'of the fluid operatedpump I8. Such operating iiuid under pressure is used, as is well known in the art, to actuate the fluid operated pump I8; and subsequently is conveyed as spent operative uid at relatively low pressure upwardly through the longitudinal passages 45 of the inlet fitting I9 to enter the annular longitudinal space 58 of the power tubing 28, through which it is conveyed upwardly through the various fittings and couplings to the separation fitting 38, outwardly through the radial port |35 thereof into the spent power fluid line 3| from which it ilows to the collection tank 32. This operation is continued until the collection tank 32 is substantially lled with operating fluid, at which time the float mechanism 4|, operating through the rod 82, closes the neat-actuated valve 48. The high pressureA pump 36 henceforth merely circulates the operating iiuid from the collection tank- 32 through the power tubing 2B and the fluidvoperated pump I8. Leakage of operating uid from the closed system of the power tubing, fluid operated pump I8, and collection tank 32, is replenished as described above. As normal leakage in the closed operating fluid system normally does not amount to as much as 1% of the vvdisplacement of the fluid operated pump i8, the auxiliary tank 31 need have only a small volumetric capacity, and the scavenger pump operated by the high pressure pump 34, likewise, need have only a relatively small flow capacity .to replenish the closed system with operating fluid as needed. l

When it is desired to remove, or pull, the power tubing 28 Vfrom the, well, it is desirable, frequently, that little of the power fluid contained therein be discharged into the production tubing I3. This may readily be accomplished -with the special power tubing 29, illustrated, due to the provision of the valve coupling. 24. The connection between the tubing sections 22h and 22e is rst broken, at the elbow fitting 29, and then the power tubing 20 is raised until the slips 21 engage the tubing section 22a just below the valve coupling 24. The tubing section 22a is then retained stationary by the slips 21, and the power tubing section thereabove is rotated together with the valve coupling 24 so as to unscrew the outer tubular coupling member 18 from the upper end of the tubing'section 22a. As the coupling `member 18 is unscrewed from the tubing section 22a it moves upwardly relative thereto, the valve assembly 86 remaining seated, temporarily, on the upper end of the tubing section 22a. Such upward movement of the coupling member 18 is continued until the valve assembly 86 seats on the vcoupling member, the outer conical valve :face 93 seating on the outer valve seat 83 in fluid-tight engagementxso that upon subsequent upward movement of the coupling member 18 power fluid in the annular space 50h and thereabove in the power tubing will be retained therein. During such subsequent upward movement of the coupling member 18, as will be apparent, the valve assembly 8B is also raised therewith so as to break the engagement of the valve assembly with the upper end of the tubing'section 22a. Continued upward` movement of the valve `assembly 83 causes the inner annular valve seat 95 to engage the inner valve member 91 in fluid'- tight engagement, which retains thereabove in the power tubing 20 any operating fluid contained in the inner tubing section 49h. After the inner valve member is thus closed, continued upward movement of the coupling member 'I8 breaks the connection between the O`ring 80 and the upper end of the outer tubing member 48a which, up to that time, has maintained a. fludetight seal between the coupling member and the tubing section 22a, and the coupling member is then disengaged from the tubing section 22a therebelow. Thus, substantially all opera-ting fluidV in the tubing section 22ois retained therein by the valve coupling 24, and the tubing section 22h and any tubing sections thereabove connected thereto may be stacked in the vicinity of the well in a vertical position without losing any of the power fluid therefrom.

When the power tubing 20 is reassembled so as to run the fluid operated pump I8 back into the well,- the operation is reversed, as will be understood. In this operation, obviously, the outer tubing coupling member I8 is moved down over the upper end of the tubing section 22a until the O-'ring 80 forms a fluid-tight seal therebetween. Upon continued lowering of the coupling member 18, the valve actuating bar 'I1 engages the lower end of the valvestem 98 to move the inner valve member 91 off its seat S5 so as to again open communication between the inner tubing members 49a, and 49h. yContinued downward movement of thecouplingr member 'I8 permits the valve assembly 86 to seat on the upper end of the tubing section 22d.v and to break connection between the conical valve facen93 of the valve assembly and the valve seat 83, so as to reopen communication between the annular spaces 50a and 50h. The coupling member 'I8' is then further screwed onto the tubing section 22a until its seating' faces IIII and |02 form fluid-tight engagement with the lower end of the tubing section 22h and the upper end of the tubing section 22a, respectively, so that sealing is not entirely dependent upon the O-rings I9 and 80.

It will be apparentfrom the foregoing` that I have providedl a closed operatingfluid system for a fluid operated pump having the advantages and fulfilling the objects setgforth above, and, further, that I- have provided a special type of power tubing and fittings therefor particularly adapted `,for use in sucha closed operating fluid system. Although I have shown and described a preferred embodiment of the invention, it will be apparent that modification thereof may be made Without departing from the' spirit of the invention, and, consequently, `III do not intend to be limited to the specific form illustrated, but desire to be afforded the full scope of the following claims.

I claim asmy invention:

1. In a fluid operated pump system, the combination of: a fluid operated pump in a vweiland having aninlet for operating" fluid under presf sure and an outlet for spent operating fluid, said pump being adapted to be actuated by the delivery thereto of operatingfluid under pressure; a production tubing extending downwardly in said well so as to receive pumpedwell fluid from 'said pump and to convey it upwardly; a power tubing extending downwardly through said production tubing and connected to said pump, said power tubing includingan inner tubing member and an outer tubing member radially spaced froml said inner tubi-ngmember',- one of saidtub'- igmembers: communicating witlrsaid inlet# and 10 being adapted to convey said operating fluid under pressure downwardly to said pump, and the other of said tubing members communicate ing with said outlet and being adapted to convey spent operating fluid upwardly from said pump, said power tubing comprising a plurality of axially aligned sections eacli of which includes a section of the inner'tubing member and a sec-V tion of the outer tubing member rigidly connected together in radiallyspaced relation; power pumping means cbnnected to said one of s aid tubing members for supplying said operating fluid under pressure unidirectionally to said one of said tubing members only; reservoir means connected toy said other of said tubing membersfor receiving spent operating fluid therefrom; Aand fluid-conducting means connecting said power pumpingmeans to saidreservoir means.l f

2. In a fluid operated pump system, the

bination of: a fluid operated pump in awwll and adapted to be actuated by the delivery thereto of operating fluid under pressure; a production tubing extending downwardly in said well so as ,to receive pumped well fluid from said pump and to convey it upwardly; a power tubing extending downwardly in said well and kconnected to said pump and including a pair of tubing members, one of said tubing members being adapted to convey said operating fluid yunder pressure downwardly to said pump and the other of said tubing members being adapted to 4convey spent operating fluid upwardly therethrough from said pump; power means for supplying said operating fluid under pressure to said one of said tubing mem-V bers; collecting means connected toy said other of said tubing members and adapted to receive therefrom spent operating fluid, said collecting means being also connected to said power means so as to' supply operating fluid thereto; a source Vof additional operating fluid; and means' for introducing additional operating fluid from said source into the intake of saidpower means to re'- plenish operating fluid lost from the system, the means last defined including valve means inter-'- posed between said sourcev and the intake ofsaid power means, and including float means respon'- sive to a predetermined reduction in` fluid level in said collecting means for actuating said valve means.

3. In a fluid operated pump system', the come' bination of a fluid operated pump' in a well and adapted to be actuated by the delivery thereto of operating fluid under pressure; a production tub: ing extending downwardly in said' well sofas toreceive pumped well fluid from said punp and'to convey it upward-ly; a powerv tubing extending downwardly said-l welll and co'rinected to saidpump' and including a pair ofuib'ing` in"einiibe'rs.I one or said tubing members being adapted to conveyV said operatingv fluid under' pressure' down; wardly to said pump and tl'ie other f said tubingmember's being adapted to' convey spent operating fluid upwardly' therethrouglr fromf'saidf' pump ;A power meansv for supplying said operatin'g fluid under pressure to said one ofl said tubing mem# bers ;v collecting means connectedv tov said' other f said tubing members and adapted to receive therefrom spent operating' fluid, said collecting means-being alsofconn'ected to said power meansso'as to supply operating fluid thereto; a-source of additional operating fluid; and means for introducing additional operating' fluid from sai-d source into the intake of said power means tore= plenish operating fluid lostfrom the system", said 11 last mentioned means operating in response to a predetermined reduction in fluid level in said co1- lecting means.

4. In a iluid operated pump system, the cornbination of a fluid operated pump in a well and adapted to be actuated by the delivery thereto of operating fluid under pressure; a production tubing extending downwardly in said well so as to receive pumped well iluid from said pump and to convey it upwardly; a power tubing extending downwardly in said well and connected to said pump and including a pair of tubing members, one of said tubing members being adapted to convey said operating fluid under pressure downwardly to said pump and the other of said tubing members being adapted to convey spent operating ud upwardly therethrough from said pump; power means for supplying said operating fluid under pressure to said one of said tubing members;rcollectingmeans connected-to said other of said tubing members and adapted to receive therefrom spent operating iiuid, said collecting means being also connected to said power means so as to supplyoperating fluid thereto; a source of additional operating fluid; and means for supplying additional operating fluid from said source to said power means when the totall volume of said operating iiuid in said system decreases to a predetermined minimum.

5. In a fluid operated pump system, the combination of: a uid operated well pump in a, well and adapted to be actuated by the delivery thereto of operating Huid under pressure; a production tubing extending downwardly in said well so as to receive pumped well iiuid from said well pump and to convey it upwardly; a power tubing extending downwardly in said well and connected to said well pump and including a pair of tubing members, one of said `tubing Y members being adapted to convey said operating fluid under pressure downwardly `lto said well pump and the other of said tubing members being adapted to convey spent operating iiuid upwardly therethrough from said well pump; a replenishingfluid source; and a surface pump at the surface of the ground having an intake connected to said other tubing member so as to receive spent operating fluid therefrom, and having an outlet connected to said one tubing member so as to convey said operating fluid therethrough under pressure, said surface pump producing unidirectional flow from said intake to said outlet, and said surface pump including auxiliary pumping means having an intake connected to said replenishingfluid source.

6. In a fluid operated pump system, the coinbination of: a fluid operated well pump in a well and adapted to be actuated by the delivery thereto of operating fluid under pressure; a production tubing extending downwardly in said well so as to receive pumped well `fluid from said well pump and to convey it upwardly; a power tubing extending downwardly in said well and connected to said Well pump and including a pair of tubing members, one of said tubing members being adapted to convey said operating iiuid under pressure downwardly to said well pump and the other of said tubing members being adapted to convey spent operating uid upwardly therethrough from said well pump; a surface pump at the surface of the ground having an intake, and having an outlet connected to said one tubing member so as to convey said operating fluid therethrough under pressure; a uid collecting tank between and connected to said other tubing member and said intake and adapted to collect spent operating iluid discharged thereinto from said other tubing member and to supply such spent operating fluid to said intake under pressure; a source of additional operating fluid; auxiliary pumping means adapted to convey additional operating fluid from said source to said intake to replenish operating fluid lost from said tubing members; and means for so actuating said auxiliary pumping means in response to a predetermined decrease in the volume of spent operating uid in said tank.

'7. In a fluid operated pump for connection to a double walled tubing providing an inner tubing passage and an outer, annular tubing passage, one of said tubing passages being adapted to convey operating uid under pressure and the other of said tubing passages being adapted to convey spent operating fluid, the combination of: uid operated pumping means adapted to be actuated by the delivery thereto of operating iluid under pressure; and an inlet member connected to the upper end of said pumping means and having a first longitudinal inlet-member passage for conveying said operating iluid under pressure to said pumping means, and having a second longitudinal inlet-member passage for conveying spent operating iiuid from said pumping means, both of said inlet-member passages communicating with the upper end of said inlet member, and having a seat at the upper end thereof adapted to be engaged in duid-tight relation by said double walled tubing with said one tubing passage in uid communication with said iirst inlet-member passage, and with said other tubing passage in fluid coinmunication with said second-inlet member passage.

8. In a fluid-operated pump system, the combination of a huid-operated pump having an inlet for operating fluid under pressure and having an outlet for spent operating fluid; a reservoir communicating with said outlet of said fluidoperated pump; pumping means having an outlet communicating with said inlet of said Huid-operated pump and having a main inlet communicating with said reservoir, said pumping means also having an auxiliary inlet; a source of operating fluid communicating with said auxiliary inlet; Valve means interposed between said source and said auxiliary inlet; and means responsive to a predetermined reduction in fluid level in said reservoir for actuating said valve means.

CLARENCE J. COBERLY.

REFERENCES CITED The following references are of record in the le of this patent:

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